DOE/MC/29264 -- 501 6 (DE96000582)

Scaling of Pressurized Fluidized Beds

Quarterly Report January - April 1995

Leon Glicksman Paul A. Farrell

July 1995

Work Performed Under Contract No.: DE-FC2 1 -92MC29264

For U.S. Department of Energy Office of Fossil Energy Morgantown Energy Technology Center Morgantown, West Virginia

BY Massachusetts Institute of Technology Cambridge, Massachusetts

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DOEAuIW29264 -- 501 6

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SCALING OF PRESSURIZED FLUIDIZED BEDS DOE

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DOENU29264 -- 501 6 (DE96000582)

Dimibution Category UC-103

Scaling of Pressurized Fluidized Beds

Quarterly Report January - April 1995

Leon Glicksman Paul A. Farrell

Work Performed Under Contract No.: DE-FC2 1 -92MC29264

For U.S. Department of Energy

Office of Fossil Energy Morgantown Energy Technology Center

P.O. Box 880 Morgantown, West Virginia 26507-0880

BY Massachusetts Institute of Technology 77 Massachusetts Avenue, Room 7-303

Cambridge, Massachusetts 02 1 39

July 1995

' . Overview

This report provides a summary of the technicd progress made during the second quarter of the third budget period on Cooperative Agreement No. DE-FC2 l-m!!C29264, "ScaliEg of Pressurized Huidized Beds."

Technical Progress ReDort

Solids Mixing:

A thermal tracer technique has been implemented in the cold mcdel of the Tidd PFBC. The thermal tracer technique involves injecting thermally-tagged particles into the bed and tracking their motion using an array of thermistors. Tracer particles are drawn in &-om the bed into an injection tube which is immersed in 2 pool of liquid nitrogen. Once the particles are cooled sufficiently below the bed temperatire, they can be reintroduced into &e bed by air injection. Currently, ten thermistor probes have been constructed along with the necessary bridge and ampiification circuits. Efforts to install and debug this system were completed during the past quarter.

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Figure 1 illustrates the thermal tracer technique. Each of the cross-hatched circles in Figure 1 represents a thermistor probe. The probes are inserted perpendicular to the irjector. Figures 2-4 present sample output from the thermistors at different times after the chilled particles are injected. Each bsir in Figures 2-4 represents the output (dimensionless temperature) of 8

single thermistor. There is a one-to-one correspondence between the thermktor probe locations shown in Figure 1 and the bars in Fi,oures 2-4, with the exception of the thermistor directly in front of the injector. The output from the injector thermistor was not shown because it would require a significantly broader scale; this would make visualizing changes in the output of the other thermistors more difficult. In the fi,pres, the tracer particles are injected at the lower right hand comer and the fluidizing gas travels from bottom to top. These conventions are shown on Figure 2.

Consideration has also been given to the use of capacitance probes to relate the local bed hydrodynamics to the mixing data. Capacitance probes have been used by researchers to measure bubble properties such as: velocity, mean pierced length, and frequency. This information is important for developing an understanding of the solids mixing process. The use of capacitance probes to measure the bubble properties was given further considzration during the past quarter, including a visit to a company which manufactures capacitance probes and the required electronics. Another option currently under consideration is the use of a fiber optic phototransistor probe. This may prove to be a less expensive approach to measuring the bubble characteristics. .

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Emphasis of Work During Next Ouarter

Efforts during the third quarter of the third budget period will focus on:

completing taking mixing data with the current probe confkpxtion, including aii investigation of lateral mixing; and

completing an evaluation of capacitance probe and phototransistor probe methods for measuring the local bed hydrodynamics, and implementing the most desbble approach.

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